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UNITED STATES PATENT OFFICE CHARLES N. IVAITE, OF RUMFORD FALLS, MAINE,ASSIGNOR TO THE ELECTROCHEMICAL COMPANY, OF SAME PL ACE.

METHOD OF UTILIZING SALINE SOLUTIONS.

SPECIFICATION forming part of Letters Patent No. 558,241, dated April14, 1896.

Application filed October 5, 1895. $erial No. 564,800. N p im n To allwhom it may concern.-

Be it known that 1, CHARLES N. WAITE, a citizen of the United States,residing at Rumford Falls, in the county of Oxford and State of Maine,have invented certain new and useful Improvements in Methods ofUtilizing Saline Solutions, of which the following is a specification. I

My invention has for its object an improved method for the utilizationof saline solutions. It is fully set forth in the followingdescription,'and its novel features are pointed out in the claim whichis appended hereto.

In the production of chlorin and of caustic by the electrolysis of achlorid of an alkaline base the solution of chlorid is subjected, in anelectrolytic cell, to the action of an electric current until theefficient working. of the electrolytic cell is interfered with by thepresence of such a percentage of the hydrate or caustic as will decreasethe efficiency of the current beyond the limit at which the cell may beeconomically operated. WVhen this occurs, the solution in thecathode-compartment of the cell is removed and new solution supplied.The solution removed has lost only about one-third of the chlorid, andthus there occurs a loss of a considerable portion of chlorid whichcannot be economically employed in the cell, owing to the presence ofthe hydrate or caustic.

In the production of chemical fiber, which is employed in themanufacture of paper, the wood fibers or chips are boiled in a digesterwith liquor containing caustic in solution.

As a result of this treatment the gum and resin in the wood areconverted into a soap and the fiber is left-free. The fiber is thenremoved and the soapy liquor containing the excess of caustic isevaporated and roasted in a rotary furnace, yielding black ash, which isrecausticised with quicklime and used over and over again, enoughefficient caustic being added to make up for the loss in recovery.

By means of my process I utilize the solution which is drawn from thecathode-compartment of an electrolytic cell and which contains, as abovestated, the chlorid of the alkaline base and a considerablepercentageusually from six toIeight per cent. of the hydrate of thebase-by employing the said solution for the treatment of the wood fiberin the digesters in the production of chemical fiber. The presence inthis solution of the chloridordinarily chlorid of sodium-does notinterfere with the use of the solution for this purpose. After the woodfiber has been boiled in this solution from the cathode-compartment ofthe electrolytic cell the fiber is washed and the soapy liquorcontaining salt and the excess of caustic is evaporated and the residuumroasted. The black ash which results from the roasting contains salt andthe carbonate of soda and some impurities, such as coal, tarry matters,and the like. I now treat this ash by lixiviating with a limited amountof water, which results in the removal of the larger proportion of thecarbonate of soda. The latter, being more soluble than the salt, will gointo solution first. The salt and the remainder of the carbonate of sodacontaining the tarry matters, &c., are then dissolved and enoughquicklime is added to causticise the carbonate of soda. The resultingdirty solution is then run into the cathode side of the electrolyticcell and subjected to electrolytic action until there is again producedin it such a percentage of the hydrate or caustic as will interfere withthe efficient and economic working of the cell by decreasing theefficiency of the current beyond the economic limit. The dirty solutionreferred to should be used only in the cathode side of the cell,

since the presence in the anode-compartment of the cell of a smallpercentage of caustic and 0f the tarry matters would destroy theefficient working of the cell. When in the operation of the electrolyticcell the solution in the cathode-compartment again contains a sufficientpercentage-of the hydrate to interfere with the working of the cell, theliquor is again used in the digesters for the treatment of fiber, andthe process is repeated.

By this method the chlorid, if chlorid of sodium be employed, can beused up entirely, only enough salt being added to make up for soda lostin the fiber from imperfect washing without any loss of efliciency inthe electrolysis and with no Waste of salt. My process is particularlydesirable in localities 'where paash, then lixiviating to remove aportion of the carbonate from the ash, then dissolving the residuumeausticizing it with quicklime and subjecting it to electrolytic actionin the cathode-compartment of an electrolytic cell, substantially asdescribed.

In testimony whereof I affix my signature in presence of two Witnesses.

CHARLES N. \VAITE.

\Vitnesses:

GEORGE D. BIsBEE, RUSSELL II. DEARBORN.

